The TagSupport class is a utility class intended to be used as
the base class for new tag handlers. The TagSupport class
implements the Tag and IterationTag interfaces and adds additional
convenience methods including getter methods for the properties in
Tag. TagSupport has one static method that is included to
facilitate coordination among cooperating tags.

Many tag handlers will extend TagSupport and only redefine a
few methods.

Field Detail

id

pageContext

Constructor Detail

TagSupport

public TagSupport()

Default constructor, all subclasses are required to define only
a public constructor with the same signature, and to call the
superclass constructor.
This constructor is called by the code generated by the JSP
translator.

Method Detail

findAncestorWithClass

Find the instance of a given class type that is closest to a given
instance.
This method uses the getParent method from the Tag
interface.
This method is used for coordination among cooperating tags.

The current version of the specification only provides one formal
way of indicating the observable type of a tag handler: its
tag handler implementation class, described in the tag-class
subelement of the tag element. This is extended in an
informal manner by allowing the tag library author to
indicate in the description subelement an observable type.
The type should be a subtype of the tag handler implementation
class or void.
This additional constraint can be exploited by a
specialized container that knows about that specific tag library,
as in the case of the JSP standard tag library.

When a tag library author provides information on the
observable type of a tag handler, client programmatic code
should adhere to that constraint. Specifically, the Class
passed to findAncestorWithClass should be a subtype of the
observable type.

Parameters:

from - The instance from where to start looking.

klass - The subclass of Tag or interface to be matched

Returns:

the nearest ancestor that implements the interface
or is an instance of the class specified